1. Field of the Invention
The present invention relates to a photoelectric transducer, and particularly to a photoelectric transducer comprising a photosensitive element formed of an amorphous semiconductor and an auxiliary light source, which permits an increased size and free selection of its form, and in which the region of the wavelength to which the transducer is sensitive as well as the amplification factor of the photoelectric current can also be changed.
2. Description of the Prior Art
A conventional photodiode is generally recognized as a photoelectric transducer. FIG. 1 is a schematic diagram of a photo-detecting circuit using a conventional photodiode as a photoelectric transducer. The structure of the photo detecting circuit of FIG. 1 will now be described.
Referring to FIG. 1, a photodiode 1 comprises an anode, a cathode, and a single crystal semiconductor having a pn junction provided between and in contact with, these electrodes. This single crystal semiconductor generates photoelectric current by the photoelectric conversion of the incident switching light 2. The anode of the photodiode 1 is connected to the negative terminal of the DC power source 3, while the cathode of the photodiode 1 is connected through a resistor 4 and an ampere meter 5 to the positive terminal of the DC power source 3.
The operation of a conventional photo detecting circuit of FIG. 1 is as follows. When the switching light 2 irradiates the photodiode 1, the light is converted into electricity by the photodiode 1, and the resulting photoelectric current is read by the ampere meter 5 to carry out the photo detection.
In a conventional photodiode, a single crystal semiconductor is used as a photosensitive element, but this photosensitive element itself is of small size, and therefore, it restricts the form and size of the photodiode itself. Furthermore, the photosensitive element formed of such a single crystal semiconductor is sensitive to a wide range of wavelengths, so that if the transducer is desired to be sensitive only to a specific wavelength, e.g. a near infrared light, the switching light which irradiates the photodiode must be split beforehand, e.g., by a filter. In addition, a conventional photodiode has a problem in that the amplification factor of the photoelectric current cannot be readily changed since it is defined by the photosensitive element itself.